Mycoplasma bovis (M. bovis) is considered to be one of the more pathogenic species of Mycoplasma and causes significant economic losses worldwide. Mycoplamsas cause severe clinical signs in cattle of all ages. M. bovis is the most frequent Mycoplasma pathogen found to cause pneumonia, mastitis, and arthritis in cattle and its etiological role has also been associated with otitis, keratoconjuctivitis, synovitis, and reproductive disorders in cows and bulls. In general, Mycoplasmas are difficult to treat since they lack a cell wall or membrane, which tends to make them resistant to several classes of commonly used broad-spectrum antibiotic treatments. Mycoplasmas differ from viruses in that Mycoplasmas are larger than most viruses and damage tissue cells by attaching to the surface of cells and destroying them, rather than by entering the cells. Animals infected with M. bovis have depressed immune responses and may exhibit signs of M. bovis infection such as fever, depression, anorexia, labored breathing, nasal and ocular discharge, coughing, sneezing, gasping, grunting, lameness and swollen joints, mastitis, middle ear infections, abortions, recumbence and death. The organism persists in unsanitary, warm, moist environments. Mycoplasmas may survive in milk, and even seem to thrive in the presence of large numbers of leukocytes, which are produced in response to the infection.
U.S. Pat. No. 6,548,069 discloses a vaccine composition that incorporates a whole cell inactivated bacterin containing at least two killed M. bovis strains and that an isolate may rapidly alter its antigens in culture. The patent teaches that high passage strains of greater than about 50 passages may lose infectivity and elicit a poorer immune response when used in a bacterin. It teaches use of a Mycoplasma strain which has been passed no more than about ten times or less before mass scale production because the antigens are believed to retain their natural state and thus will elicit a protective immune response against the infectious microorganism.
Killed M. bovis is not as effective or efficient as desired in lessening the severity of clinical symptoms associated with a Mycoplasma bovis infection. Even passage at a low level does not produce a Mycoplasma vaccine with high efficacy such that clinical symptoms are greatly reduced in animals when compared to animals not receiving such a vaccine. The few low passage, inactivated, M. bovis vaccines that are available do not show a large reduction in the severity of clinical symptoms in animals when compared to animals not receiving such vaccine.
The nature of the market requires that farmers be able to effectively immunize their animals for a wide variety of conditions in an efficient way. Other conditions that would be suitable for efficient immunization include, but are not limited to, Bovine viral diarrhea virus (BVDV), Parainfluenza-3 virus (PI-3), Bovine Respiratory Syncytial Virus (BRSV), Bovine Herpesvirus (BHV-1), Bovine rotavirus, Breda virus, a calici-like virus, Adenovirus, Astrovirus and Parvovirus, Mannheimia haemolytica (formerly Pasteurella haemolytica), Pasteurella multocida, Actinomyces (Arcanobacterium) pyogenes, Haemophilus somnus (reclassified as Histophilus somni), Chlamydiae, Bovine genital campylobacteriosis, Leptospirosis, Brucellosis, Clostridia, Escherichia coli, Cryptosporidium parvum, Mycobacterium avium paratuberculosis, Salmonella, Mycobacterium avium paratuberculosis, Cryptosporidiosis, mastitis, Dermatomycoses, lower respiratory tract infections, Trichomoniases, Neospora Canum, Babesiosis and the like.
There remains a need for an immunogenic composition effective for eliciting an immunological response against M. bovis for lessening the severity of or reducing the incidence of signs of M. bovis infection, and for reducing or eliminating the incidence of signs of M. bovis infection.